1. Field of the Invention
The invention relates generally to railroad end of train units, and more particularly to an improved method for keeping track of end of train units.
2. Discussion of the Background
Within the railroad industry, end of train (EOT) units are typically attached at the rear of the last car on a train. As is well known in the art, these EOT units can perform one or more of a variety of functions. EOT units monitor air pressure in the air brake pipe and transmit this information to the head of the train (HOT). EOT units also often include an end-of-train marker light. Two-way EOT units can accept a command from the HOT to open the air brake pipe (loss of air pressure in the air brake pipe causes the brakes to activate and stop the train) in an emergency situation. Some EOT units include motion detectors that are used to inform the HOT as to whether, and in some cases in which direction, a train is moving. Other EOT units include GPS receivers that are used to transmit location information pertaining to the end of the train to HOT equipment as discussed in U.S. Pat. No. 6,081,769. EOT units usually communicate with the HOT using radio-based communications.
Supplying power to EOT units is an important consideration. As discussed in U.S. Pat. Nos. 5,267,473 and 6,236,185, it is known to supply power to EOT units using batteries or a combination of batteries and air-powered generators connected to the brake pipe. In order to conserve battery power, EOT units are usually configured to power down when the unit is tipped over from a vertical orientation to a horizontal orientation by trainyard personnel when the EOT is not in use.
As their name implies, EOT units are mounted at the end of a train. Because various cars in trains are often shuffled in and out of consists and because trains are often reformed during operation, it is often necessary to install and remove EOT units from individual cars in a train yard. Because EOT units are often heavy and/or bulky, EOT units removed from cars are often left by the wayside for collection at a later time. Unfortunately, EOT units left by the wayside in this manner often become misplaced or “lost.” Thousands of wayside units are lost this way each year. Even a temporarily misplaced EOT unit can cost a railroad money. For example, rent must be paid for the time when an EOT unit from one railroad is in another railroad's territory. Thus, if such an EOT unit is temporarily misplaced, the rent is increased.
What is needed is an apparatus and method for tracking EOT units.